Never wrestle with a pig, you both get dirty and the pig enjoys it.
(This was from an unregistered member "Dave" on HVAC-Talk)
The ones I lived by for many years...
"If you're going to be Stupid, You'd better be Tough".
"If somebody gets Hurt, I won't be the last one".
I like the Pig one, it's 100% true.
Yes, I know I Shouldn't But I Just Can't Help Myself...
One of our local inspectors had this posted on his wall but his said. Arguing with the inspector is like wrestling a pig. You both get muddy and the pig enjoys it.
I like: Never try to teach a pig to sing! It's a waste of your time and it annoys the pig.